Impulse transmitter



Aug. 14, 1945. R. c. MATHES IMPULSE TRANSMITTER- Filed Aug. 5, 1943 2Sheets-Sheet 1 M w y lNl fNTOR RC. MA THES Q lt-d.

A TTORNEY Patented Aug. l4, 1945 UNlTED STA" TRANSMETTER ApplicationAugust 5, 1943, Serial No. 497,538

d Glaims.

This invention relatesto impulse transmitting devices and moreparticularly to telephone call transmitters of the key-operated type.

It is the object of this invention to provide an impulse transmitter ofthe key-operated type which embodies characteristics that are particu--larly desirable from the-users standpoint and which functions totransmit series of correctly timed impulses without imposing any unduereautomatically to transmit the predetermined number of impulses at apredetermined desirable speed or frequency independently of any controlby the manually operable means. More particularly, the transmitter ofthis invention embodies an impulse counter comprising a plurality ofmanually displaceable resilient balls which may be selectively dividedinto groups containing one to ten balls to .correspondingly predeterminethe number of impulses to be transmitted, and electromagneticallycontrolled, mechanically tuned means for individually restoring theballs of a selectively displaced group of balls and for simultaneouslyoperating a set of pulsing contacts once for each ball individuallyrestored.

In the particular embodiment of the invention disclosed in the drawingsa row of ten balls is normally confined between two oppositely disposedpoles of a permanent magnet. The balls are arranged in consecutivecontiguity in such a manner that the last ball of the row abuts one ofthe permanent magnet poles and the first ball of the row is spaced fromthe other permanent magnet pole. A group of ten individually manuallyoperable keys is arranged in superposed relation to the row of balls,each key being so contoured as to function, when depressed, as a cammingdevice for displacing one or more balls from their normal positions andfor moving the said balls in such a direction that the first ball of theselectively displaced group of balls contacts the other permanent magnetpole. The

'number of balls thus displaced is determined by the particularkeyactuated and predetermines the number of impulses to be transmitted.An

electromagnetic interrupter is rendered eiiective at a particular stagein the operation of a key and functions through a mechanically tunedstriker or hammer to repeatedly strike the permanent magnet pole againstwhich the selected group of balls has been moved to cause one ball ofthe selected group of balls to be returned to its normal position foreach impact of the striker against the permanent magnet pole. Thestriker functions simultaneously to operate a set of pulsing contactswhich, in reality, constitute the interrupter contacts of theelectromagnet. When the last ball of the selected group is restored toits normal position the circuit of the electromagnetic interrupter isopenedand operation of its pulsing contacts is discontinued. Thus thenumber of balls displaced incident to the actuation of a keypredetermines the number of impulses to be transmitted and the tunedstriker functions to count oil the predetermined number of impulses at aspeed or frequency corresponding to the frequency of vibration of thestriker.

A feature of the invention resides in the use of manually operable keysfor selectively displacing the balls which have normal, fully depressedand intermediate positions whereby the ball camming portion of the keyafter having been fully depressed to displace a particular group ofballs is returned to its intermediate position in which it clears theballs and thereby allows freedom of movement of the balls in theirreturn to normal positions under control of the tuned striker.

Another feature of the invention contemplates the use of switching meanswhich function when a key is fully depressed for preparing theelectromagnetic interrupter for inclusion in thepulsing circuit andwhich complete the effective inclusion of the interrupter in the pulsingcircuit only when the key has attained its intermediate position. Thisfeature precludes the premature operation of the pulsingcontacts andprecludes the functioning of the interrupter until the ball movin camportion of the key has been removed from the line of travel of theballs. This feature also precludes the false operation of thetransmitter should the operating subscriber hold a key in its fullydepressed position for an abnormal interval of time.

In accordance with another feature or the invention latching means isprovided which functions to lock an actuated key in its intermediateposition. An ancillary feature provides means whereby the last ballrestored to normal position under the influence of the tuned strikerserves to operate the latching means and to effect the restoration ofthe actuated key.

These and other features of the invention will be better understood fromthe following detailed description when read in connection with theaccompanying drawings, in which:

Fig. 1 is a front elevation of the impulse transmitter of this inventionmounted within the base of a telephone set;

Fig. 2 is a view of the impulse" transmitter taken along the line 2-2 ofFig. 1, looking in the direction of the arrows;

Fig. 3 is a view of a portion of the impulse transmitter taken along theline 3--3 of Fig. 2, looking in the direction of the arrows;

Fig. 4 is a view similar in part to that shown in Fig. 1 and shows thetransmitter with one of the manually operable keys in its operatedposition; and

Fig. 5 is a combined circuit and structural schematic illustrating thevarious switching elements controlled by the transmitter and theirlocations in the line circuit of a telephone subscribers station.

A permanent magnet consisting of an elongated flat piece i and twooppositely disposed integrally formed pole-pieces H and I is secured tothe base |2 of the telephone set 9 by means of screws l3. Fixed to thepiece l0 also by the screws I3 is an insulating trough-like member 14.This member 14 is made up of a base piece which rests upon the magnetpiece l0 and two integrally formed sides which extend the entire lengthof the permanent magnet. The upper ends of the member H are turned in topartially enclose the area defined by the insulating base piece, its twosides and the permanent magnet poles l4 and I5. This insulatin structureforms a race or receptacle for ten balls l6 of resilient magneticmaterial. The receptacle H is slightly longer than the space occupied bythe ten balls when in contact one with another and the partial enclosureeffected by the inturned upper edges of the sides precludes thepossibility of the balls falling out of the receptacle while permittingthem freedom of motion therein.

The U-shaped permanent magnet serves to hold the balls in the normalposition illustrated in Fig. 1 and also in whatever positions the ballsare moved to incident to the actuation of the keys 29. The balls l6 areso normally positioned in the receptacle N that the ball on the extremeright of the row, viewing Fig. 1, touches the permanent magnet pole l5and the ball on the extreme left is spaced from the pole I. As aboveindicated, the ten balls are held in this position by the action of thepermanent magnet.

Brackets II and I! are fixed to the base l2 by screws 23. Thesebrackets, located one at either .end of the base, provide means formounting a slidable latch plate 2|, a fixed plate 22 and a stop membercomprising two angularly disposed integrally formed portions II and IT.

The latch plate 2| is provided at each end with a slot 23 and isslidably held on the upper flanges of the brackets I3 and I 3 by screws2| which screw into the bracket flanges in such a manner that the shankportions of the screws constitute guides which pass through th slots 23and allow the plate 2| to move freely longitudinally. The plate 2| isprovided with ten spaced apertures or oriflees 27 for a purpose to beset forth hereinafter.

The plate 22 is stationary and is fixed to the brackets l8 and I! byscrews 23. This plate 22 is located below the slidable latch plate 2|and is provided with ten circular openings 30 and a larger substantiallyrectangular aperture 44 located near the left end of the plate.

The stop member comprising a weighted portion 40 and a stop portion I1is pivotally mounted on a rod 41 which is supported by two integrallyformed arms 42 of the bracket Hi. The hole or aperture 44 in plate 22permits freedom of movement of the stop member when pivoting on the rod4|. A spring 43 having one end fixed to the underside of the weightedportion 40 and its other end fixed to a pin mounted on the upper edge ofpermanent magnet pole l4 assists in restoring the stop member to itsnormal position, illustrated in Fig. 1. In this position the stopportion I1 is located between the inner face of pole 4 and the ball ISon the extreme left of the row.

The ten balls l6 are displaceable from normal to alternate positions ingroups of one to ten balls by means of the keys 29. Each key 29 consistsof a shank portion 3|, a camming portion 28 and a button, designated 29,all of which are formed integrally, or associated in such a manner as toconstitute a unitary structure. The shank portion 3| of each key islocated immediately over one of the balls l6 and has its end beveled forengaging its respective 'ball and camming it to the left when the key ismanually depressed. A coil spring 33 is wound around the shank portion3| of each key and has one end embedded in the shank and the other endfixed to the stationary plate 22. These springs serve to restore thekeys after manual actuation and automatic release by the latch plate 2|,as will appear from a later de scription.

The cam section 28 of each key, interposed between the shank and button,has one edge beveled and is provided with a detent or catch 36projecting from the lower opposite edge. when a key is depressed, thebeveled edge of the cam portion 28 acts upon the edge of a correspondingaperture 21 in plate 2| and cams the plate to the left. As indicatedmore clearly in Fig. 4, the keys 29 have normal, intermediate and fullydepressed positions. As the key is depressed, the beveled end of itsshank portion 3| engages the ball l6 directly below it and cams theball, and all other balls to the left in the row, so as to move it, orthem to their alternate positions, in which the first ball on the leftof the row contacts the permanent magnet pole I. This alternate positionof the balls is attained when the actuated key is fully depressed. Itwill be observed that when a key is fully depressed the catch 36 hasmoved considerably below the under surface of the latch plate 2| so thatwhen the finger is removed from the depressed key the spring 33associated therewith functions to restore the key to its intermediateposition, in which the catch 38 engages the under surface of the plate2| causing the key to be locked.

A cam bracket 38 is fixed to the under-side of the-latch plate 2| bymeans of screw 33 and, as shown in Fig. 1, normally is in contact withthe end of the weighted portion 40 of the stop member. When the plate 2|moves to the left, incident to the operation of a key, the stop iscaused to rotate on its rod 4| in a counter-clockwise direction. In thismannerthe stop portion I1 is raised from its normal position to permitfree movement of the balls IE to the left. It will be observed,

by referring to Fig. 4, that the first ball in the row serves to furtherraise the stop and when the first ball contacts the pole it the stopportion 11 rests thereon and is held thereby in the positionillustrated. when any group of balls is moved to the left so as tooccupy their alternate positions they are held by the action of thepermanent ma net.

The purpose of providing three positions for the keys 29 is to removethe shank portions thereof from the path of the balls it after actuatingthem to their alternate positions and thereby allow the balls to bereturned to their normal positions without interference from the keyshanks. In their intermediate positions the key shanks are lifted clearof the balls as shown in Fig. 4 and do not hinder the balls in theirreturn movement. It is obvious from Figs, 1 and 4 that the first key 29to the left functions, when depressed, to move the first ball i8 to theleft of the row into engagement with pole H; the second key functions tomove the first two balls; the third key moves the first three balls, andso on.

The shank portion 3| of each key is provided with a projecting pin it!which normally clears the upper edge of a pivotal member 65. This memheris mounted on a rod 84 carried by the earlike extensions 85 of abracket. The bracket 66 is located to the rear of the permanent magnetand is secured to the base M by screws .81.

This bracket is substantially of the same length as the pivoted member63 and carries two inte rally formed lugs 93 and 94 against whichsimilarly formed lugs 9i and 92 on the pivoted member 63 rest when themember $3 is in its normal position. The member '83 is held in itsnormal position by the-action of coil springs Nib, one end of each ofwhich is fixed to the, member 83, the other ends being fastened to thestationary plate 22. The purpose of the pivotal member 53, which iscommon to all keys, is to operate springs 60, M, 8| and 65 carried bybracket b8 and more specifically to move spring iii out of engagementwith spring Wand spring bi into engagement withspring Bil during thedownstroke of the keys, and to permit the spring st to reengage spring85 and spring hi! to disengage spring 80 when the key assumes its lockedintermediate position. The actuation of springs 8i and 81' is efiectedby arms 82 and 82 respectively which extend from the right of the member83. The

, functions of springs 88, 80'. Si and l will appear from a laterdescription. Suffice it to say at this time that when 'a key assumes itsintermed ate position spring 8i reengages spring 80 before spring 6imoves out of engagement with spring 60'.

Secured to the left central portion of the base I2 is a bracket 45.Viewing Fig. 3, this bracket 45 is provided with a forwardly projectingextension to which the electromagnet 48 is secured by screws. Thebracket 45 is contlguously associated with the core 41 of the magnet 46and constitutes a portion of the magnetic circuit. The

lower end of the bracket 45, still viewing Fig. 8, is provided with avertical. extension which coop:

, crates with an L-shaped bracket Si in supporting the armature 49 andcontact springs 50 and 90. The bracket BI is secured to the base I! byscrews.

.The springs 5b and 90 are insulated from the armature 49 and from eachother, while the armature makes direct contact with the verticalextension of bracket 45. The armature 49 carries a polepiece 48 injuxtaposition to the free end of ma net core 41. Atits extreme outer endthe armature carries a ball 52 which is similar in construction anddimensions to the balls l8. The armature 49, with its pole-piece 48 andball 52, is designed to vibrate, at a particular predeterminedfrequency, or speed which corresponds to the speed at which it isdesired to transmit pulses. The spring 98 is associated with the magnetarmature 19 in such a manner that it responds faithfully to any movementof the armature. Thus, when the armature is attracted by the magnet 46the spring 80 is moved out of engagement with spring 58 and when theelectromagnet is deenergized the armature releases and causes spring 90to reengage spring 50. The purpose of these springs will be set forth indetail in connection with a description of Fig. 5 to be madehereinafter.

The first ball 16 to the left of the row of balls has fixed thereto aspring 55 which extends inwardly from the ball. This spring functions,when operated, to actuate the make-before-break springs 58 and 51. Thesprings 58 and 51 and the rear end of spring 55 areinsulatively'supported between two L-shaped brackets 85 fixed to thebase i2 by screws. The insulating receptacle 14 is cut away at H'll topermit movement of the spring 56.

Referring now to Fig. 5, the subscriber's subset S is normally connectedto the line L by way of contact springs 58 and 51. The circuit for theelectromagnet 48 extends from one of the line conductors and includescontact springs 58 and 90, winding of magnet 48, normally closedcontacts 80 and 8! and spring 55 which is normally disengaged fromspring 58. Thus the winding of magnet 48 is normally excluded from theline circuit L. When a key 29 is depressed; one Or more balls I8 aremoved to the left so that the first ball to the left of the rowengagesthe permanent magnet pole i4. As the first ball moves to itsalternate position the spring 55 moves so as to cause spring 56 todisengage spring 51. It will be recalled that during the depression ofany key 29 the pivoted member 83 is engaged by the pin 10 associatedwith the depressed key and moves so as to operate the spring pile-upcomprising contact springs 8B, 8!, 86' and 8|. Since the member 83functions during the downstroke of the key and spring 85 functions whenthe key is fully depressed, the

springs 60, 8|, and 6| are operated before the contact springs 58, 5t"and 55. The springs 80' and 8| accordingly close to maintain the subsetS across the line pending the reconnection of magnet 46 to the line andthereby to preclude the possibility of a lost connection, it beingunderstood that the contacts 58 and 51 open when the key is fullydepressed and thus open one of the substation connections to the line.Thus when the key is fully depressed the subset S is still connected tothe line and the circuit to magnet 48 is opened at springs 80 and 8|.When the key is released and-thereby assumes its intermediate lockedposition, contact spring 8| reengages spring 80 just prior to theseparation of contact springs 80' and 8| so that the winding of magnet48 is effectively includeddn the line circuit. The circuit for magnet 48includes the contact springs 58 and 88, winding of magnet 48, closedsprings 80 and 8|, and springs 55 and 58. The purpose of springs 88 and8| is to preclude the effective inclusion of magnet 48 in the line Luntil the depressed key has been released and has assumed itsintermediate locked position. Unless such precaution is taken and themagnet is included in the line when the key is fully depressed it wouldimmediately start to operate as an interrupter to actuate latch platedisengages the pulsing contacts "-40 and this operation of the magnetwould persist as long as the operator or subscriber maintained the keyin its fully depressed position. The consequent operation of the pulsingcontacts would result in false connections.

When the magnet 48 is effectively included in the line circuit itfunctions as an interrupter on current from the source 93 located at acentral oflice. Obviously the magnet would function indefinitely as aninterrupter to operate springs 50 and 90 and correspondingly effect thetransmission of impulses since the springs 50 and 90 are connected inseries with the line and the winding of the magnet. However, the numberof times the armature 49 operates and therefore, the number 01' timesthe pulsing circuit is interrupted to transmit impulses is determined bythe number of balls that have been moved to their alternate positionsincident to the actuation of a key. For example, assuming the fourth keyfrom the left is actuated,

four balls ii are moved to the left so that the first 1 ball thereofcontacts permanent magnet pole ll. When the magnet 48 starts to operateas an interrupter, the ball 52 fixed to the armature 43 of the magnetstrikes pole ll once for each energiration of the magnet. Upon the firstimpact of ball 52 on pole II the fourth ball of the selected group isdriven back to its normal position; the second impact causes the thirdball to be returnedto its normal position; the third impact causes thesecond ball to return to its normal position; and the fourth impactreturns the first ball 'to its normal position, When the first ball isreturned to its normal position, the spring 55 restores to normalcausing spring 56 to reengage the spring 51. Thus the operating circuitfor magnet I8 is opened. at spring 51 and the subset S is reconnected tothe .line. The opening of the circuit to magnet 46 precludes any furtheroperation of the armature l9 and any further operation or the pulsingsprings 50, and the electrical circuit assumes its normal unoperatedcondition. Thus, four pulses are transmitted incident to the actuationof the fourth key.

When the first ball in the row is returned to normal as described above,the stop "-41 falls back to its normal position due to the action ofgravity on the weighted portion and to the action of spring 43. Theweighted portion 40 thus engages the cam bracket 38 and cams the Latchplate 2| to the right. This movement of the the catch 36 and permits thedepressed key 29 to restore to normal under the action of its spring 33.The member 63 thereupon returns to normal and the springs 60, BI and GIrestore. The transmitter is thus restored to normal.

In practice, each key of the impulse transmitter of this inventioncarries designation characters or symbols corresponding to thoseappearing on the number plate of the well-known flngerwheel dial. Forexample, the first key would bear the numeral 1"; the second key, thecharacters ABC2; the third key, the characters DEF3; etc.

.The telephone set casing is provided with ten cylindrical compartments30 in which the button end of the key 29 moves when depressed. Thediameter of the compartments is slightly greater than that of the collar34 associated with each key so as to permit free movement of the keystherein.

A stop 8| is provided on the pole l4 and provides a rest for the stopIll-I1.

The transmitter of this invention functions to transmit a number ofimpulses corresponding to the number of balls selectively displaced bythe manual operation of any of a plurality of keys, and the selectednumber of impulses is transmitted at a frequency or speed determined bythe mechanical tuning of the electromagnet armature.

While the embodiment of the invention described in the specificationinvolves the use 01 magnetic balls, it is readily apparent that thetransmitter is not limited to the use of such balls and that it willfunction equally well with nonmagnetic balls provided some simpleexpedient is resorted to in holding the balls in their normal andalternate positions. Such means may take the form of non-linear springsor toggles, the principle of operation of such mechanisms being wellknown.

What is claimed is: V

l. The combination, in an impulse transmitter, of an electromagnet, anarmature for said electromagnet, pulsing contacts controlled by saidarmature, and an impulse counter comprising a row of ten resilientmagnetic balls, a magnetic circuit for holding said balls normally incontact with one another comprising a permanent magnet having twooppositely disposed poles against one of which the last ball of said rowrests, manually operable key means having fully depressed andintermediate positions, means controlled by said key means when fullydepressed for selectively dividing said row of balls into two groupscontaining one to ten balls and moving a selected group so that thefirst ball of the selected 4 group is moved into engagement with theother pole of said permanent magnet, means controlled by the first ballof the selected group when thus moved for preparing an operating circuitfor said electromagnet, means for locking said key means in itsintermediate position, means controlled by said key means in itsintermediate position for completing the operating circuit for saidelectro magnet whereupon said electromagnet causes said armature tovibrate and actuate said pulsing contacts, means controlled by saidarmature when vibrated for repeatedly striking the other pole of saidpermanent magnet to cause the balls of the selected group to be drivenback individually to their normal positions,'means controlled by thefirst ball of the selected group when driven back to its normal positionfor opening the operating circuit for said electromagnet, and othermeans controlled by said first ball for releasing said key means.

2. An impulse transmitter for use at a telephone subscriber's stationfor transmitting impulses suitable for actuating automatic switchesemployed in extending a call initiated at the said station, comprising,in a unitary structure, a normally positioned row of contiguouslyassociated balls, a plurality of manually operable keys corresponding innumber to the number of balls in said row and each key having normal,fully depressed and intermediate positions, pulsing contacts, anelectromagnet having a vibratable armature for controlling saidcontacts, a normally open control circuit for said electromagnet, meansintegral with each of said keys and eilective when its corresponding keyis fully depressed for moving a predetermined number Of the balls ofsaid row from their normal positions, means for restoring the fullydepressed key to its intermediate position, means effective only whensaid key has been fully depressed and then restored to its intermediateposition for closing the cono,ss1,o7s

' trol circuit of said eiectromagnet whereupon said.

electromagnet functions to vibrate its armature and said pulsingcontacts are operated once for each vibration of said armature, meanscontrolled by said armature for restoring one ball of said predeterminednumber of balls to its normal position for each vibration of saidarmature, and means controlled by the last ball restored for opening thecontrol circuit of said electromagnet and for restoring said key to itsnormal position.

3. The combination, in an impulse transmitter, of pulsing contacts, avibratable member for operating said pulsing contacts once tor eachvibration thereof, an electromagnet for vibrating said member, aplurality of balls normally contiguously associated so as to form acontinuous row, a

normally open operating circuit for said eiectromagnet, a plurality ofmanually operable keys each having a normal, a fully depressed and anintermediate position, means controlled by each of said keys whenmanually moved to its fully depressed .position' for separating apredetermined number of balls from the said continuous row of balls,means controlled by one of the balls I of the separated predeterminednumber of balls for preparing the operating circuit for saidelectromagnet, means for initiating the return of a fully depressed key,means for arresting the return movement of the key so as to maintain itin its intermediate position, means controlled by the key when in itsintermediate position for completing the operating circuit for saidelectromagnet whereupon said electromagnet functions to vibrate saidmember, means including said member for restoring a ball oi saidpredetermined number of balls to normal position for each vibration ofsaid member, and means controlled by the said one of said balls foropening the .operating circuit to said electromasnet and forsimultaneously restoring the key to its normal position. v

a The combination, in an impulse transmitter, of an eiectrcmagnet, anarmature for said electromagnet, pulsing contacts controlled by saidarmature, and means for predetermining the number of operations of saidpulsing contacts by said armature comprising a row of resilient magneticballs, a magnetic circuit for holding said balls normally in contactwith one another comprising a permanent magnethaving two oppositelydisposed poles against one of which the last ball of said row rests, aplurality of manually operable keys having normal, fully depressed andintermediate positions, means integral with each of said keys andeffective upon the full depressionoi said keys for physically engagingsaid balls so as to separate said row into two sections and for movingone of said sections so that the first ball of said ro engages the otherpole of said permanent magnet, means controlled by the first ball whenthus moved for preparing an operating circuit for said electromagnet,means for returning said keys from their fully depressed positions,means for arresting said keys in their intermediate positions, meanscontrolled by said keys in their intermediate positions for completingthe operating circuit for said electromagnet whereupon saidelectromagnet causes said armature to vibrate and actuate said pulsingcontacts, means controlled by said armature when vibrated for drivingthe balls of the said moved section to their normal positions one at atime, means controlled by the said iirst ball of said row when drivenback to its normal position for opening the operating circuit to saideleetromagnet, and other means controlled by the said first bail forrestoring said key to their normal positions.

a '1 ROBERT C.

